If you’re trying to lose weight and eat healthier, chances are you’re well aware of the benefits of logging your food. While setting calorie goals and balancing macronutrients are largely tried-and-true tools, one metric is a bit more controversial.
Enter net carbs, aka “impact carbs” or “active carbs,” a category of carbohydrates that’s increasingly marketed on food packaging. An invention of food marketers, net carbs emerged with the low-carb and keto diet craze as more people started counting (and avoiding) carbs in the hopes of losing weight.
Net carbs are calculated by taking the total amount of carbohydrates in a food and subtracting dietary fiber and sugar alcohols (low-calorie sweeteners like erythritol and xylitol) which, theoretically, aren’t digested by your body. Because you aren’t absorbing these carbs as energy, they “don’t count.” For example, a protein bar with 15 grams of carbs, 9 grams of dietary fiber and 2 grams of erythritol would have a total of 4 net carbs.
While some nutrition professionals view net carbs as distracting or misleading, others argue they’re well worth considering. Here, experts take sides on whether or not counting net carbs is worth your time:
Counting net carbs is simple to do and it can make life a bit easier when you’re trying to lose weight. To work toward your total carbohydrate goal (which a registered dietitian can help you figure out), all you have to do is subtract the fiber and sugar alcohols from total carbs and continue on with your day.
Net carbs are tricky because every person is different and no particular approach is appropriate for everyone. It’s important to remember that carbs are not the enemy, and just counting net carbs doesn’t tell the whole story when it comes to overall nutrition. For example, there’s a significant difference between foods that are low net carb and very high in fat versus foods that are low net carb and very high in fiber.
Focusing on net carbs is an unnecessary approach to healthy eating and weight loss and can cause more confusion than benefit. Focusing on net carbs can also potentially lead to over-consumption of carbs and highly processed foods. Just because something is labeled ‘low net carbs’ doesn’t mean it’s a healthy food you can eat without considering the portion size or calorie count. It’s much more important to learn how to look at nutrition from a holistic perspective and eat a variety of foods rather than following one rule.
If you’re working to lose weight or build muscle, factoring in net carbs can help since your body isn’t absorbing certain carbs for energy (aka, calories). In particular, people living with diabetes can benefit from focusing on net carbs; carbs from fiber do not impact blood sugar since they aren’t absorbed by the body. If someone with diabetes took insulin based on total carbs without considering fiber, they might have a higher chance of ending up with low blood sugar.
If you need to watch your blood sugar or stick to a ketogenic diet, you might benefit from considering net carbs. This could be the case if you have hard-to-manage diabetes or a certain neurological condition that calls for this diet, like a seizure disorder. In either case, though, a doctor should be monitoring any severe carbohydrate restriction.
The only real nutritional impact of being aware of net carbs is it may help you choose foods that are higher in fiber, which can help improve your digestive health and decrease your risk of cardiovascular disease. However, just because a food has more fiber doesn’t guarantee it has an overall more nutrient-dense makeup. For instance, laxatives are primarily made of fiber, but we wouldn’t consider them a nutritious supplement.
In some cases, counting net carbs without considering the type of fiber can be misleading when it comes to controlling your blood sugar. For example, isomalto-oligosaccharides (IMOs), a lab-created fiber commonly found in protein bars, is absorbed by the body nearly as fast as sugar and can impact your blood sugar levels. However, for fruits, veggies, grains and the majority of whole foods, net carbs are generally advantageous.
Net carb calculations aren’t always 100% accurate. While some fibers (like insoluble wheat bran, for example) are completely indigestible and contribute zero calories, some soluble fibers (like gums and pectins you often find in processed foods) are partially digestible — which means they do add some calories to your diet.
When you place a large emphasis on net carbs, you ignore the fact that the protein and fat content of your food also impacts how quickly the food is absorbed. Having a balanced meal of protein, fats and carbs allows your body to slowly absorb nutrients and have more sustained energy rather than a quick burst of energy followed by a crash. Furthermore, having to track yet another thing in order to lose or maintain your weight can be stressful.
While experts are split on whether or not focusing on net carbs is worth it, they do agree on one thing: No matter your goal, it’s essential to eat a variety of nutritious and satisfying whole foods. Rather than taking the “low net carbs” label at face value, take a look at how much fiber a food actually contains (and, if necessary, what type) before you assume it’s healthy or a good fit for your specific dietary needs.
If you’re trying to slim down or maintain your current weight, Harris-Pincus recommends an eating plan that’s both high in fiber and low in net carbs. Instead of making it a contest to see how low you can go with carbs, aim to eat at least 25–35 grams of fiber each day to fill you up and help minimize hunger pangs, she suggests. Loading your plate with nutrient-rich whole grains, non-starchy vegetables like broccoli and kale, beans and high-fiber fruit, like berries, can help you meet your fiber and net carb goals.
Finally, remember: “To lose weight you need to create a slight calorie deficit where you burn more calories than you eat, regardless of your net carbs count,” says Herrenbruck.
Stick to your low-carb goals by tracking total net carbs in each food, meal and day in the MyFitnessPal app.